- 2 days ago
Air Crash Investigation Series S23E03 Pressure Point
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TVTranscript
00:00Japan Airlines Flight 123 crashes into a mountain, killing 520 people.
00:10It's the deadliest single aircraft accident in history.
00:14We were working in this terrible carnage. I get chills thinking about it.
00:20Investigators immediately suspect an act of terror.
00:23Right now it's a bomb. That's what the crime guys are telling us.
00:26But the wreckage tells a different story.
00:28There's no fire damage.
00:30No shrapnel damage.
00:32What they soon discover...
00:34It was the only thing holding the two sides together.
00:37...threatens to ground one of the most popular commercial jets on the planet, the 747.
00:43We were concerned that we had a structural flaw in the airplane and others were worried too.
00:53Baby, baby!
00:58It's 6.10pm at Tokyo's Haneda Airport.
01:20Japan Airlines Flight 123 is ready for departure.
01:24Number one engine, start.
01:31In the left-hand seat is 39-year-old First Officer Yutaka Sasaki, training to become a 747 captain.
01:40I'll handle the radios while you fly.
01:41The captain is Masami Takahama, a former military pilot who joined Japan Airlines 20 years ago.
01:51Flight plan calls for a right turn out.
01:56Haneda ground.
01:57Japan Air 123, request taxi, Charlie 7.
02:03Thank you, sir.
02:11Today's flight is full with 509 passengers on board.
02:16It's the start of the Obon holiday.
02:18Obon is a Buddhist event about the ancestors' spirits.
02:26It happens in summer.
02:28People in the city go back to their hometown with families to celebrate.
02:33It's the start of the day to celebrate.
02:3926-year-old Yumi Ochiai is an off-duty flight attendant.
02:42I'm so glad to have a break for the holiday.
02:49Yumi Ochiai was like many young Japanese.
02:53She wanted to see the world.
02:55Working for the airlines allowed her to do that.
03:05V1.
03:08Rotate.
03:0930 minutes before sunset, flight 123 lifts off.
03:17Positive rate.
03:18Gear up.
03:24Very nice.
03:27Flight 123 is one of dozens of 747s carrying passengers throughout Japan.
03:33To this day, the 747 is the most iconic jetliner ever built.
03:41When it debuted in the 70s, it was by far the biggest commercial plane that had ever flown.
03:47And every pilot wanted to fly this plane.
03:50To meet growing demand for cheap travel within Japan,
03:54Boeing designed the 747SR, a special version of the jumbo jet.
03:59The 747SR, or short range, was an unusual variant in that it was designed for high-density, short-haul operations.
04:09The Minister of Transportation was on the last leg.
04:14Hope you gave him a smooth flight.
04:16Assisting on tonight's trip is flight engineer Hiroshi Fukuda.
04:22He's flown on 747s since they were introduced to Japan Airlines in the 1970s.
04:29These earlier 747s required three pilots.
04:33The third pilot being a flight engineer, who sat behind the captain and first officer,
04:37controlling all of the airplane's systems and subsystems that were later consolidated
04:41into the more computerized, to-pilot airplanes that we have today.
04:46For 10,000, flight level 240 selected.
04:55It's an hour-long flight from Tokyo to Osaka, one of Japan's busiest domestic routes.
05:0111 minutes into the flight, Japan Airlines 123 approaches its cruising altitude.
05:14OK, 1,000 feet to go and we'll level off.
05:17Yes, sir.
05:19As they near 24,000 feet, the crew settles in for what's expected to be a smooth flight.
05:25If an airplane is suddenly displaced by some violent force, the autopilot can suddenly kick
05:37off, and the pilots now have to take control and physically steer the airplane again.
05:43Something exploded?
05:46I'm squawking 7700.
05:49Putting 7700 into the transponder is a way of broadcasting an urgent situation.
05:55Was that a gear door?
05:57Check gear.
05:58What about the engines?
06:01All engines are good.
06:03When something unusual or sudden happens, pilots are trained to stop, analyze, evaluate the situation
06:11before simply reacting.
06:14Look at this.
06:1616 seconds after the explosion, the pilots realize the cabin is losing pressure.
06:21If an airplane depressurizes anything over 20,000 feet or so, now suddenly you don't have oxygen
06:30to breathe.
06:31Put on your oxygen mask.
06:33Fast seatbelts.
06:34We are making...
06:35The emergency masks provide only 15 minutes of oxygen.
06:39Just enough oxygen for an emergency descent to below 10,000 feet.
06:43Something exploded.
06:46Something exploded.
06:50Right turn.
06:52Right turn.
06:54Tokyo, Japan Air, 123.
06:57Having trouble.
06:59Request return back to Haneda.
07:02Descend and maintain 220.
07:03Over.
07:04Roger.
07:05Right heading 090.
07:06The pilots of flight 123 attempt a sharp turn back to Haneda airport, now 70 miles behind
07:16them.
07:19Don't bank so much.
07:20Okay.
07:23The R5 door is broken.
07:25We're making an emergency descent.
07:27Don't bank so much.
07:31Hydraulic pressure is dropped.
07:32While the crew tries to determine why the cabin depressurized, they face an even more serious
07:39problem with the hydraulic systems.
07:45Without the hydraulic pressure, it's very difficult to move the control surfaces.
07:56Don't bank so much.
07:58It's manual.
07:58The decrease in hydraulic pressure is making it difficult for the first officer to stop
08:04the dangerously steep right turn.
08:07Turn it back.
08:09It won't go back.
08:14Hydraulics are all out.
08:18Nobody in that cockpit had ever seen a complete hydraulics failure.
08:24There was no checklist, no procedure for how to deal with that.
08:28Descent.
08:32The pilots are unsure if their control inputs are doing anything.
08:38What's going on?
08:44He's not turning back to Haneda.
08:47Air traffic controllers are puzzled by flight 123's erratic flight path.
08:52Why isn't he descending?
08:53Why isn't he descending?
08:55Japan Air 123, confirm.
08:57We're declaring an emergency.
08:59Affirmative.
09:00Request.
09:01Nature of your emergency.
09:03Uncontrollable.
09:05Uncontrollable.
09:06Roger.
09:06Understood.
09:11Put your heart into it.
09:13Yeah.
09:13If you've lost pitch control, elevator control, an airplane will fall into an oscillating series
09:20of climbs and descents, a fugoid.
09:23The plane will pitch up until it runs out of speed.
09:27It will then nose down into a descent.
09:29It will pick up speed and momentum.
09:31And as the wings begin to generate more lift, the plane will again begin to climb.
09:37The pilots try using engine power to turn the airplane towards Haneda.
09:43By increasing power on the left side, the plane would turn to the right.
09:47Increasing power on the right side, the airplane would turn to the left.
09:50It works.
09:58The 747 starts a slow turn to the right.
10:03We are making an emergency descent.
10:05Put on your oxygen mask.
10:07Fasten seatbelts.
10:08Don't worry, the pilots have turned us back.
10:09We will be landing in Haneda soon, okay?
10:11Put on your oxygen mask.
10:12Fasten seatbelts.
10:15Still at 22,000 feet, the captain can see Haneda in the distance.
10:2081 miles away.
10:22Can you hold?
10:24The crew reflexively thought, let's get this plane back to Haneda.
10:29And why Haneda and not somewhere closer?
10:31Because they were familiar with Haneda.
10:34Haneda is within reach.
10:35But the plane's erratic behavior is worsening.
10:39And the pilots are at breaking point.
10:41In the cabin, emergency masks are running out of oxygen.
10:53Fasten seatbelts.
10:55We are meeting an emergency.
10:58I don't understand what's happening.
11:06For 14 minutes, the crew of Japan Airlines 123 has been struggling to control their 747.
11:14They can't get the plane to descend.
11:19Gear down.
11:22Lowering the landing gear, dumping all of that machinery down into the airstream,
11:27will slow a plane down by vastly increasing the amount of drag, helping it to descend.
11:32It doesn't work.
11:35The gear won't go down.
11:38Let's try the alternate.
11:42In an emergency situation, like a hydraulic failure,
11:46the crew can lower the landing gear with gravity.
11:49However, once the gear is down, it cannot be pulled back again.
11:55Lower.
11:55Lower.
11:56Yes.
11:57Yes.
11:58Gear coming down.
12:00Really, they're just trying desperation moves here,
12:03trying to find the right configuration to stabilize the plane as best they can.
12:12Keep the nose down.
12:14Yes.
12:15With the landing gear down, the aircraft begins to slow.
12:23We are descending now.
12:2515 minutes after the incident began,
12:28Japan Airlines 123 is finally losing altitude.
12:32The gamble has paid off.
12:34It's not in what I would call controlled flight,
12:37but it's a steadier condition than it was in,
12:39and it's descending now into lower altitudes where passengers can breathe again.
12:49Hold it here.
12:53We're over Lake Sagami.
12:56Just ahead, the pilots see the familiar lights of Tokyo.
13:02But the captain's optimism vanishes when the plane suddenly banks hard to the left.
13:09This may be hopeless.
13:13Lower the nose more.
13:16Request radar vectors to Haneda.
13:19Roger, understood.
13:20Keep heading 090 for runway 22.
13:24Whoa!
13:25As the plane descends below 10,000 feet,
13:28the situation worsens.
13:32It's uncontrollable again.
13:34Watch out for the mountain.
13:35So then, it suddenly begins descending at a high rate of speed
13:41directly towards the mountains.
13:43Japan Airlines 123 is flying directly away from Haneda Airport,
13:48heading straight towards high terrain, north of Mount Fuji.
14:01Right, Turner, we will hit the mountains!
14:03Yes!
14:06Nine minutes after lowering the landing gear,
14:09the plane has descended 15,000 feet.
14:19Where did he go?
14:23Flight 123 drops below the peaks of the surrounding mountains,
14:28out of range of Tokyo's radar.
14:30Max power!
14:38Max power!
14:44Incredibly, the pilots are able to arrest the dramatic dive.
14:47The plane begins a very abrupt pitch-up.
15:03So much so that now they're very worried about the airplane stalling
15:07at the top of that climb.
15:08When the airspeed drops to 108 knots,
15:14the stick shaker activates.
15:18Increase power!
15:22Not good!
15:23We're stalling!
15:24The plane slows to 108 knots,
15:28which is beyond the stall margin for a 747.
15:31How they didn't just drop out of the sky at that point,
15:33I'm not sure.
15:36We're losing altitude!
15:38Raise the nose!
15:40The flight crew is exhausted.
15:43For 25 minutes,
15:44they have fought for control
15:45as they continue to fly away from Haneda Airport.
15:50Flaps!
15:51The first officer suggests deploying the flaps,
15:54which may help them stabilize the airplane,
15:57allow them to fly at a slower speed without stalling.
16:00Extend the flaps!
16:01Flaps coming out!
16:03Because the normal hydraulic deployment
16:06is obviously unavailable.
16:08When flaps are deployed electrically,
16:10they come out very, very slowly.
16:12For more than a minute,
16:19flight 123 flies almost normally.
16:26Left turn!
16:28As the crew attempts a left turn back to Haneda,
16:31the plane banks hard to the right.
16:35Japan, air 123, request position.
16:38Your position is 45 miles northwest of Haneda.
16:42Unknown to the pilots,
16:44the flaps on each wing
16:45are extending at different speeds.
16:48What's happened is the flaps on the left side
16:50have come down faster than the flaps on the right side.
16:53This has caused the left wing
16:54to produce a lot more lift,
16:56which is turning the plane hard to the right.
17:00The nose!
17:01The uneven flaps make the situation worse.
17:05The nose!
17:064,000 feet from the ground,
17:08Japan Airlines 123 is dropping fast,
17:12losing 15,000 feet a minute.
17:16Raise the nose!
17:17Raise the nose!
17:20Quite soon, we will be making a vert and land.
17:25The pilots use all their strength to regain control.
17:29I can't hold it much longer!
17:33But nothing works.
17:34Flaps up!
17:36Flaps up!
17:37Flaps up!
17:44Raise the nose!
17:45Up!
17:46Power!
17:47Up!
17:48Up!
17:48Up!
17:50Don't think!
17:50Japan Airlines flight 123 has crashed into a mountain
18:05in a remote area northwest of Tokyo.
18:08When rescuers reach the crash site the next morning,
18:17they find devastation.
18:22Only the left wing and rear section of the aircraft are recognizable.
18:26As rescuers examine the tail section,
18:33they make an astonishing discovery.
18:35There are four survivors.
18:39To have made it out and survived the next 15 or so hours under the wreckage in the wilderness,
18:46I don't know how it happened, but it did.
18:48520 people have died, the deadliest single-plane crash in history.
18:58Japan's Air Accident Investigation Commission, or AAIC, is soon joined by experts from the NTSB and Boeing.
19:06We were working down there in this terrible carnage, and family members had already been brought up to the mountain,
19:15and they built little altars.
19:18And that's, that's, I get chills thinking about it.
19:20One of the survivors is Yumi Ochihae, the off-duty flight attendant.
19:29She's able to talk?
19:32Though injured, Yumi is able to speak to investigators.
19:36Yumi, can you tell me what you remember?
19:39We were ascending when something exploded behind me.
19:46Investigators discover that 12 minutes into the flight over Sagami Bay,
19:50there was an explosion.
19:55The survivor's account gives investigators their first big clue.
20:03After the sound of the explosion,
20:06Mrs. Ochihae saw white fog.
20:10And this white fog is a result of a sudden decompression.
20:13Immediately after decompression,
20:14the flight attendant describes seeing a hole in the fuselage.
20:27Based on the survivor's account, investigators are immediately suspicious.
20:44Right now it's a bomb.
20:48That's what the crime guys are telling us.
20:52Japan is already on high alert.
20:56Two months before the crash,
20:58a bomb detonated at Narita Airport.
21:00On the same day that an Air India 747 fell from the sky off the coast of Ireland.
21:08There was all kinds of concern internationally and in Japan
21:12that we had a terrorist group trying to blow airplanes out of the sky.
21:16Let's keep an open mind and look for something else.
21:21Even if you think it might be a bomb, that's speculation.
21:24The 747 was one of the more popular airplanes in service at this time.
21:29And we were worried that if it was something else,
21:32it might ground the airplanes.
21:36Make sure we catalog everything.
21:38With the black boxes sent off for analysis,
21:41investigators examined the wreckage in an aircraft hangar.
21:45Let's test for explosive residue near the back.
21:48I had this package of glass bottles and cotton swabs and tweezers and alcohol and water
21:55and diligently swabbed the AFLAV walls and sent the samples back to the company in Seattle.
22:08To reconstruct the final 30 minutes of the flight,
22:13they turn to the radar track.
22:17Almost 24,000 feet over Sagami Bay.
22:21Yeah.
22:22As investigators zero in on how and where the incident began,
22:27they get a break.
22:29Hey, that's our plane.
22:32A witness on the ground took a photo of the plane during the incident.
22:38A piece of the tail missing.
22:40A vertical stabilizer is pretty much gone.
22:45Losing a vertical fin has never happened to an airliner this big before.
22:51The airplane had lost most of its tail.
22:54And it makes sense that investigators were focused on the possibility of an in-flight explosion, a bomb.
22:59Missing tail, and Yumi Ochia said there was a hole behind her.
23:05It all adds up.
23:07But we need the tail to prove it.
23:08The day after the crash of Japan Airlines Flight 123,
23:17part of the missing tail is found floating in Sagami Bay, south of Tokyo.
23:27So what do you think?
23:29Investigators examine the tail, looking for any clues that point to a bombing.
23:34There's no fire damage.
23:38No shrapnel damage.
23:40But that's not what they find.
23:43Nothing really looks like bomb damage.
23:46There's a lot of telltale signs.
23:48I saw none of that.
23:52Until they get the swab results back from the lab,
23:55they can't rule out a bomb entirely.
23:57So you were the controller that handled Japan Air 123, right?
24:02Correct.
24:04Investigators speak to the controller,
24:06who was in contact with the crew for 32 minutes.
24:09Did the pilot say anything about what happened to the plane?
24:12Right from the start, they said it was uncontrollable.
24:17Did they say why?
24:18No.
24:19But they did mention to dispatch something about damage to a door.
24:24No.
24:27The R-5 door is broken.
24:31We're making an emergency descent.
24:37It's very helpful.
24:39The pilot reported that the door may have come off,
24:43and there was a concern that if the door came off,
24:46it may have damaged the airplane.
24:50The right rear door is here, behind our survivor.
24:53Maybe that's the opening our survivor described.
24:58That would explain the depressurization.
25:01There's a precedent there.
25:02In 1974, the cargo door of a Turkish Airlines DC-10 had blown off,
25:08causing instant decompression of the cabin
25:12and failure of the cabin floor,
25:14resulting in the loss of flight control.
25:16The door is big, so you can definitely do damage to the tail.
25:26Enough damage to knock it right off the plane?
25:28Several days after the crash,
25:42the right rear door is found.
25:45Looks like the door was locked.
25:48And it was found with the rest of the wreckage.
25:51So it didn't fall off in flight.
25:53It was a good theory.
26:04I know.
26:07We're missing something.
26:08We are back to square one.
26:25No trace of explosives found on the wreckage.
26:30Flight 123 was not brought down by a bomb.
26:34Well, one thing's for sure.
26:37Something happened in the back of that plane.
26:40Was there a structural issue?
26:42Was there a design issue even,
26:44which might affect more 747s than just this one?
26:49We really needed to get an answer to that.
26:52We need to reassemble it, too.
26:58While investigators focus on the rear of the plane,
27:01the Japanese government orders inspections of all 747 tail assemblies.
27:08Around the world, the safety of the 747 is questioned.
27:13There was moves by the Europeans and the Brits to ground the 747,
27:19and that would have had terrible economic impact on the United States.
27:24So from their first emergency call to the crash,
27:31it was almost 32 minutes.
27:35The team turns to the cockpit voice recorder for clues.
27:40Let's hear it.
27:43Get quick.
27:47Sounds normal.
27:48It's just a flight attendant asking for something on the intercom.
27:50Whoa.
28:00Something exploded?
28:03We know that was definitely not a bomb, but did you hear that?
28:08Let's roll it back.
28:15Yeah, I heard that.
28:17That was two explosions.
28:18We didn't know what the boom, boom was when we heard it on the CVR.
28:26Okay.
28:27Let's assume that the first explosion was a decompression somewhere behind you.
28:32What about the second one?
28:34Let's just keep listening.
28:38Don't bang so much.
28:39It's manual.
28:42Turn it back.
28:43It won't go back.
28:44Hydraulics are all out.
28:51The 747 has four hydraulic systems
28:55that control the rudder,
28:57elevator,
28:59ailerons,
29:00flaps,
29:00and landing gear.
29:01Two booms and no hydraulics.
29:08Yeah, they had a lot to deal with.
29:11For investigators, it's an important clue.
29:15If you lose all your hydraulic systems on the airplane,
29:18you don't have any control of the flight controls.
29:20It's no wonder they told ATC they were uncontrollable.
29:27So having gone away from the door,
29:30we began focusing on the aft end of the airplane.
29:37Somehow they're all connected.
29:39Let's try to pinpoint the cause of the decompression.
29:57The team scours the reconstruction of the tail section
30:00of Japan Airlines Flight 123,
30:03looking for evidence of what caused the first explosion.
30:06The United States needed to determine the cause of this accident
30:11because we manufactured the 747.
30:15We were concerned that we had a structural flaw in the airplane
30:18and others were worried too.
30:21Okay, let's start here.
30:22The rear pressure bulkhead.
30:28The rear pressure bulkhead stands more than four meters high.
30:33Shaped like an umbrella,
30:34it acts like a cork in a champagne bottle,
30:37keeping the cabin pressurized.
30:40Any explosion in the rear of the aircraft
30:43could explain the sudden depressurization.
30:46That's when we decided we need to focus on that area,
30:49on the bulkhead,
30:51and see what happened there.
30:55The team recovers the rear pressure bulkhead
30:58from the crash site
30:58and painstakingly reconstructs it over several days.
31:09So this is it, huh?
31:11Yeah.
31:14At 24,000 feet,
31:15that's over a quarter million pounds of pressure.
31:18It's a lot of force.
31:19The rear pressure bulkhead has to hold the pressure
31:23inside the airplane.
31:25It's got to be very, very strong.
31:27It's got to be fail safe.
31:29And it needs to do its job reliably.
31:33Look, this damage here is from the crash.
31:37These rips are from the plane slamming into the mountain, yeah?
31:40One of the things that investigators are trained to do
31:43and eventually learn to do
31:45is to look for anything that's out of the ordinary.
31:48Check this out.
31:53This isn't crash damage.
31:55This is a rupture.
31:56Yeah, and a clean one at that.
31:58Look, it runs mainly along this line of rivets.
32:04The straight-line fracture
32:06certainly piqued our curiosity
32:08as to what this was all about.
32:10Investigators discover a rupture
32:1441 inches long.
32:19Because of this long, flat area that we saw,
32:24it made us very curious
32:25that this thing had ruptured instantaneously
32:28and caused this explosive decompression.
32:31What could have caused the long rupture?
32:48What do you have?
32:50The team examines a piece of metal
32:52from where the rupture occurred.
32:54There's striations.
32:56Lots of them.
32:57Under close examination,
33:00they discover a web of radiating contours
33:03called striations.
33:05They are tell-tale signs of growing cracks.
33:08Every time a little fatigue progresses,
33:10it leaves a mark,
33:12what they call striations.
33:14It's long-term metal fatigue.
33:15Yeah.
33:16Every flight,
33:17every time they pressurized the cabin,
33:18those fatigue cracks would have grown.
33:20If microscopic cracks
33:24form under rivets
33:26on the pressure bulkhead,
33:27they would continue to grow
33:28with the forces of the plane
33:30being repeatedly pressurized.
33:35So once the airplane's in service,
33:37these cracks start developing,
33:39but they start under the rivet heads
33:40where you can't see them,
33:42and even once they progress outside,
33:45they're very difficult to see
33:46because they're only a few millimeters long.
33:50Why did the cracks form in the first place?
33:53Yeah.
33:54The pressure bulkhead's
33:55one of the strongest parts of a 747.
33:58The design philosophy
33:59for the pressure bulkhead
34:01included a fail-safe design.
34:05If this rear pressure bulkhead
34:06had a fatigue crack begin,
34:08it would stop
34:09because there's a piece
34:10called a crack stopper.
34:11The rear pressure bulkhead
34:14consists of five bays.
34:17Each bay is separated
34:18by a strap or crack stopper
34:20designed to contain a small crack,
34:23preventing it from spreading
34:24to other bays.
34:28So why did this rupture
34:30spread beyond the crack stopper?
34:32Investigators dig into
34:33the maintenance history
34:35of the aircraft.
34:35Maybe this will help.
34:41This plane had a previous accident.
34:44Seven years earlier,
34:46the plane had an incident
34:47landing in Osaka.
34:50It suffered a hard tail strike.
34:54Severe damage to the rear pressure bulkhead.
34:57Keep going.
34:59Bottom of the bulkhead was crushed,
35:02sent for repairs.
35:03In this Osaka incident,
35:08the airplane's tail
35:10did hit the runway pretty hard.
35:12And it wore through the skin
35:14and actually damaged some structure,
35:17including the rear bulkhead.
35:22Instead of replacing
35:24the entire bulkhead,
35:26Boeing engineers decided
35:27to replace only
35:28the damaged lower half.
35:31Once the repair is made,
35:32it should be as strong
35:35or stronger than
35:36when the airplane
35:36was originally made.
35:41Well, this is the original bulkhead.
35:44This is the new bulkhead.
35:48Maybe the repair is the issue.
35:51This kind of cracking
35:53in the same area
35:54that the repair was
35:55was really more
35:57of a coincidence
35:59than we could have
36:00imagined.
36:04So how did you fit
36:05the new bottom
36:06to the top of the bulkhead?
36:09Investigators look
36:09into the 1978 repair
36:11more closely.
36:13That was a really big job.
36:17Technicians worked
36:18around the clock
36:19for eight days
36:20inside the plane
36:21to mount and secure
36:22a new lower bulkhead
36:24to the upper section.
36:26Did you notice anything
36:27out of the ordinary?
36:28Well, there was only
36:29one small thing.
36:32Just a little higher.
36:34During the repair,
36:36technicians had difficulty
36:38connecting the upper
36:39to the lower pieces.
36:40There's not enough overlap.
36:43What do you mean?
36:44We had trouble
36:45fitting the overlap
36:46at the nine o'clock position.
36:48The difficulties
36:51with the repair
36:52match exactly
36:53where the bulkhead failed.
36:57Okay.
36:58Thanks for your help.
36:59Investigators
37:00are now confident
37:01that the repair
37:02seven years ago
37:03is connected
37:04to the crash.
37:07Now we're getting somewhere.
37:13Okay.
37:14Normally,
37:14the top and bottom
37:15are held together
37:16with two rows of rivets.
37:18Yeah?
37:19Investigators
37:20scrutinize the repair job
37:22to Flight 123's
37:23pressure bulkhead.
37:25Right.
37:26And they did that
37:27everywhere
37:27except for right here.
37:29One area
37:30of the bulkhead,
37:31the skin
37:32did not overlap enough.
37:34Boeing had to
37:35design a patch,
37:38a repair.
37:39It was called
37:40a splice.
37:42Without enough space
37:43for two rows
37:44of rivets
37:45in the overlap,
37:46a separate splice plate
37:47is attached
37:48over the area.
37:51But only one row
37:53of rivets
37:53showed signs
37:54of metal fatigue.
37:55It's hard to tell
37:56how the repair
37:57was done.
37:58We knew
37:59that there was supposed
37:59to be a splice plate there,
38:01but it was evident
38:03to me
38:03that there was just
38:05one row of rivets
38:06taking up the load.
38:07It didn't look right.
38:09They used two different
38:19splice plates.
38:23And by using
38:24two different splice plates,
38:26they compromised
38:27the repair.
38:32Investigators discover
38:33the repair team
38:34cut the splice plate
38:36in two,
38:36perhaps for easier
38:38installation.
38:39The lower plate
38:41helped secure
38:42the overlap.
38:43The upper plate
38:44did not.
38:48That one row
38:49of rivets
38:50was insufficient
38:51to sustain the loads
38:52and eventually
38:53fatigue cracks
38:55started
38:55and the whole
38:57section failed.
38:59The fracture
39:00followed the gap
39:01between the two
39:01splice plates.
39:07This particular
39:08747SR
39:10had accumulated
39:10over 18,000 cycles
39:13in its 12-year career
39:15with JIL.
39:15That's just an
39:16astonishing number.
39:17V1.
39:21Rotate.
39:23Each one of those
39:24cycles,
39:24each one of those
39:25takeoffs and landings
39:26meant pressurization
39:27and depressurization
39:29cycles.
39:30The rear bulkhead
39:31now had a weak spot.
39:34It was sort of like
39:36a ticking time bomb
39:37ready to fail.
39:39That's it.
39:40That's got to be it.
39:42It's what investigators
39:44call the golden nugget.
39:46We found the
39:48aha,
39:49that's the cause.
39:52There's no question
39:53that if done correctly,
39:55the repair
39:56would not have failed.
40:00Investigators
40:01have discovered
40:01what caused
40:02the rapid decompression.
40:04But they still
40:05need to understand
40:06why the tail detached.
40:09The bulkhead
40:10rupture's here
40:10and all that
40:12pressurized cabin
40:12air has got
40:13to go somewhere.
40:15Now,
40:15the shockwave
40:16flows up the tail
40:17and it must have
40:20just popped off
40:20like champagne cork.
40:24The first boom
40:25was the failure
40:26of the bulkhead
40:27and the second one
40:30was after the vertical tail
40:32pressurized
40:32and it failed.
40:33hey, check this out.
40:45All four hydraulic lines
40:47run through the tail section.
40:50So when the decompression
40:51happens,
40:52not only do they lose
40:53a chunk of that tail,
40:55they lose all those lines
40:56as well.
40:56In this case,
40:58all four hydraulic lines
41:00went up the vertical fin,
41:02so that was a poor design.
41:06It was just considered
41:08so unlikely,
41:09so inconceivable
41:10that all four systems
41:11would in some way
41:12be disabled,
41:13but that's exactly
41:14what happened.
41:18It's a design flaw
41:20that rendered
41:20the rest of the plane's
41:21flight controls useless.
41:24Don't bank so much.
41:25Hydraulic pressure is dropped.
41:33Without any hydraulics
41:34to control elevators,
41:36rudder or ailerons,
41:38Flight 123
41:39flew an erratic flight path
41:41for 32 terrifying minutes.
41:45Raise the nose.
41:47Raise the nose.
41:50The two pilots
41:52used all their strength
41:53to regain control.
41:54I can't hold it
41:56much longer.
41:58But nothing worked.
42:00Flaps up.
42:01Flaps up.
42:03Flaps up.
42:10Raise the nose.
42:12You're right.
42:13Power.
42:13What began as a repair
42:16seven years earlier
42:17set the stage
42:19for a devastating crash.
42:24that took the lives
42:27of five hundred and twenty people.
42:31The worst single aircraft
42:33accident of all time.
42:42The initiation and propagation
42:44of the fatigue crash.
42:45A series of recommendations
42:46takes direct aim
42:48at the original 747 design.
42:50operators are ordered
42:53to install a cover
42:54in the tail
42:55to protect the vertical fin
42:57against a bulkhead decompression.
42:59The improper repair.
43:01Emergency cutoff valves
43:03are also recommended
43:04to prevent a total loss
43:06of hydraulic pressure.
43:07One way they can do this
43:09is to put what they call
43:11fuses
43:11in a hydraulic system.
43:14If you cut
43:14the line
43:15the hydraulic fluid
43:18would be trapped
43:18in the rest of the line
43:20and they were installed
43:21on the 747.
43:24Today
43:24hydraulic fuses
43:25are used on
43:26almost every
43:27commercial airline.
43:28This accident
43:35was a watershed moment
43:37in aviation safety.
43:41It pointed up
43:42a lot of areas
43:43that not only
43:44the 747
43:45but other airplanes
43:48flying could be improved
43:50right then
43:51and for the future
43:53and for future designs.
43:54there is no
43:57it does.
43:58I could do it
43:59with the
44:00kids.
44:00I'm the
44:00third one.
44:01I could do it
44:01with the
44:02�를
44:03and the
44:04kids..
44:04I could do it
44:05with them...
44:05I could do it
44:06again.
44:06But I would
44:08get a little
44:09to try
44:11the next one.
44:12The
44:13Lonely
44:14is a
44:14part of
44:16the
44:17tron
44:17will
44:18and
44:19I can
44:20find
44:21the
44:21cool
44:21and
44:22to
44:22see
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44:00
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